leu·​cism ˈlü-ˌsi-zəm How to pronounce leucism (audio)
: an abnormal condition of reduced pigmentation affecting various animals (such as birds, mammals, and reptiles) that is marked by overall pale color or patches of reduced coloring and is caused by a genetic mutation which inhibits melanin and other pigments from being deposited in feathers, hair, or skin
leucistic adjective

Examples of leucism in a Sentence

Recent Examples on the Web The all-white giraffes had leucism, which causes the loss of pigmentation, creating white skin. Caitlin O'Kane, CBS News, 21 Aug. 2023 Some other animals are just partially white due to a different condition called leucism, which impacts melanin production in only some areas of the body. Carolyn Hagler, Smithsonian Magazine, 1 June 2023 The Olive Ridley Project, a sea turtle conservation group, states that sea turtles with leucism typically have a hard time surviving because of a lack of camouflage. Fox News, 19 Oct. 2020 In humans, leucism typically manifests itself in patches of white hair and lighter skin, Beckmen said. María Luisa Paúl, Washington Post, 28 Nov. 2022 However, the moose’s coloring could be the product of a nutritional deficiency while in utero or of a genetic condition called leucism — the partial loss of pigmentation. María Luisa Paúl, Washington Post, 28 Nov. 2022 If the eyes are a normal color for that species, the bird has leucism. al, 20 Apr. 2022 Adams attributes the unusual coloring to leucism, a condition where melanin is only partially lost and some parts of the penguin's body retain color, reports Live Science. Elizabeth Gamillo, Smithsonian Magazine, 23 Feb. 2021 Instead, the coloration comes from a genetic condition called leucism, which is a partial loss of pigmentation that still leaves dark coloring in the animal’s eyes, tail hair and spots. Theresa MacHemer, Smithsonian Magazine, 27 Nov. 2020 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'leucism.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


borrowed from German Leucismus, from Greek leukós "clear, white" + German -ismus -ism — more at light entry 1

First Known Use

1878, in the meaning defined above

Time Traveler
The first known use of leucism was in 1878

Dictionary Entries Near leucism

Cite this Entry

“Leucism.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/leucism. Accessed 3 Dec. 2023.

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